West Nile is a virus that can cause illnesses or fatal encephalitis (also called inflammation of the brain) in people, horses, many types of birds and possibly other animals. It spreads through the bites of infected mosquitoes, but there is no evidence to suggest that it can be spread from person to person or from animal to person.

Where Did It Come From?

The virus has been commonly found in humans and birds and other animals in Africa, Eastern Europe, West Asia and the Middle East. But it wasn't reported in the Western Hemisphere until 1999. It is not known from where the U.S. virus originated, but it is most closely related to strains found in the Middle East.

Symptoms

If a human is infected with the virus, it multiplies in the person's blood system and crosses the blood-brain barrier to reach the brain. Symptoms include fever, headache and body aches, occasionally with skin rash and swollen lymph glands, although some people have no symptoms. There is no vaccine against West Nile encephalitis, although several companies are working to develop one. Less than 1 percent of those infected with West Nile virus will develop severe illness.

Protect Yourself

Cases of human illness from West Nile virus have been rare, and the odds of becoming ill from a mosquito bite are low. Reduce your chances further by avoiding mosquito bites:Eliminate standing water from around your home.

Pay special attention to discarded tires. That is where lots of mosquitoes breed.Clean clogged roof gutters every year, particularly if the leaves from surrounding trees have a tendency to plug up the drains. Millions of mosquitoes can breed in roof gutters each season.

Turn over plastic wading pools when not in use. A wading pool becomes a place for mosquitoes to breed.

Turn over wheelbarrows and do not let water stagnate in birdbaths. Both provide breeding habitats for domestic mosquitoes.

Aerate ornamental pools or stock them with fish. Water gardens can become major mosquito producers if they are allowed to stagnate.

Clean and chlorinate swimming pools when not in use. A swimming pool left untended by a family on vacation for a month can produce enough mosquitoes to infest an entire neighborhood. Mosquitoes may even breed in the water that collects on pool covers.Use landscaping to eliminate standing water that collects on your property. Mosquitoes may breed in any puddle that lasts for more than four days.

Make sure that doors and windows have tight-fitting screens. Repair or replace screens that have tears or holes in them.

Check around faucets and air conditioner units and repair leaks, eliminating puddles that remain for several days.

If You Find A Dead Bird ...

Many people now know that the virus can kill many types of birds and that dead birds in your neighborhood may mean that mosquitoes carrying the virus are in the area. Most of the time, the bird's death was not caused by the virus. However, if you see a dead bird, you should tell your local or state health department. They may choose to pick up and test the bird for the virus.

Sources: Centers for Disease Control and Prevention, Ohio State University, and the Colorado Department of Health